COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Bell Helicopter Textron Canada (BHTC) 222 Series Helicopters AD/BELL 222/15 Main Rotor Yoke 7/89 Applicability: All helicopters fitted with main rotor yoke P/N 222-011-102-101. Requirement: Modify yoke assembly in accordance with Bell Alert Service Bulletin 222-88-51. Compliance: Prior to issue for Australian Certificate of Airworthiness. Background: Investigation of a cracked main rotor yoke has determined that the crack resulted from fretting. A yoke assembly modification has been developed that will add a buffer pad under the yoke bushings and replace the existing bushings with a larger flange version. The flapping bearing buffer pads are also replaced with larger diameter pads.